Art or process of liquefying and separating mixed gases.



J. F. PLACE.

ART ORPROCESS v0F LIQUEFYING ANDSE PARATING MIXED GASES. APPLIcVATIoIIFILED FEB. I1. I9II.

l91-9l 19, Patented Aug. 31,1915.

' component parts, oxygen and nitrogen, I

entran srAfrEs ra'ranr carica.. I*

JAMES F. PLACE, OF GLEN RIDGE, NEW JERSEY, ASSIGNOE. 'lO AMERICAN AIR-LIQUEFYING COMPANY, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

naar or, raocEss 0E LIQUEEYING AND SEPARATING MIXED tGASES.

, Specimen? of Letters Patent. Patendpmg, 31, 1915,

Application led February 17, 1911. Serial No. 609,210.

To allvwwm it may concern:

Be it known that I, JAMES FQ PLACE, a citizen of the United States, andresident of Glen Ridge, in the county ofEssex and State of. New Jersey,haveginvented certain new and useful Improvements in the Art or` Processof Liquefying and Separating Mixed Gases, of which the following is aspecification.

My invention relates to an improved art or .process of liquefying andseparating mixed gases into their component elements. One object of myinvention is to simplify and lessen the cost of apparatus required tocarry out the process and reduce the cost of liquefaction andseparation.

Byk my present process I make use of expansion against externalresistance of a part of the mixed gas treated, so as to transform a partof the heatk of the gas as expanded into recoverable external work.

rIhis process is especially adapted to liquefaction of atmospheric airand its separation into its component parts oxygen and nitrogen.

By my improved process, when used for liquefying air and separating itinto its utilize the liquid oxygen or liquid rich in oxygen as produced,after release from pressure, to sub-cool the oxygen liquid or liquidrich in oxygen before such release, as illustrated'in my United StatesPatents No. 918,468 and No. 927,5911.- In this way excessivevaporization and loss of liquid when released from the high pressure atwhich it is produced to substantially vati mospheric pressure, isavoided; forvthe liquid when released is practically cooled down to orbelow its boiling point at atmospheric pressure. y .e .i

By my improved process Il make use of my improved liquid delector andcone coil shown in my application Serial NoD 409,011

in combination with the ordinary rectify-- ing column.This'liquefyingcoil is preferably made in the shape of a frustum of aninverted cone, and of helically coiled pipes, the coils being solderedtogether so that no` liquid can pass between the coils but is kept onthe inside,.drippingcataract like vfrom one coil successively to anotheruntil the lower end of -the cone is preached. An especial feature of myinvention when used for liquefying and separating the gases ofatmospheric air is the fact that I make u Se of compressed nitrogen gasor a portion of the gaseous residue eft after partial liquefaction ofcompressed air for vexpansion against external resistance in theexpansion engine whereby a good part of the heat thereofl is convertedduring expan- `sion into external work.

a In order that those skilled in the art may clearly understand andma'ke use of my invention, I will describe myl improved process asillustrated by the 'accompanying drawing, in which I show indiagrammatic formthe'diderent parts 4of an improved apparatus, wherebywith suitable mechanism the process may be availed of.

In the drawing at the numeral 1 I show an ordinary 3-stage aircompressor, capable of compressing to suitablepressure and intercoolingand nally cooling to ordinary normal 'temperature air or other gases orgaseous mixtures, being driven by the electric motor 2, or some othersource of power. At 3 I show an air expansion engine, which may be ofthe reciprocating typeas shown, or a tiirbine, being belted to the fly-Y wheel 41 of the compressor, so as to transmit its power to and doexternal work thereon.

At 5. is represented in vertical section a rectifying column, such asordinarily used in alcohol or other distillation, but being constructedin this instance so as to be especially adapted to hold the necessaryparts for the partial liquefaction and distillation of atmospheric air.

At 6 and 7 I show two drums in elevation, one (6) containing calciumchlorid, for absorbing moisture, andcalcium chlorid brine for. catchingdust, etc., and the other (7) containing caustic potash. for absorbingmoisture and carbonio acid gas, from the compressed air or other mixedgas, -as'deliv- `ered from the compressor `(l) through the pipes 8.

At 9 I showal freezing drum, and at 10 an interchanger drum, both invertical section, 'the latter containing a high pressure lcounter-current. coil pipe 11, and the irstcontaining a high-pressuremoisture.- freezing coil pipe 12, which will be'referredto later on. Thecounter-current compressed aircoil 11 vdelivers tothe liquefying coneconduit or prima-,ry4 liqueer 13 through the connecting pipe 11. Thelower end of the liquefying cone conduit or primary liquefier isextended down by several coils as indicated at 13c which are slightly1separated as is clearly shown. The connecting pipe 11 has preferably twodeliveries to the liquefying cone coil (13), one at 11l1 near the topand one at 11 near the bottom, through thevalves 15 qr 15',respectively.

-When the compressed air is delivered to the liquefying cone 13, throughvalve 15 (which is the preferred inlet) valve 15 is closed and thecompressed air passes down through the cone, and that which .is notliquefied passes out through pipe 11c and up through the pipe 16 andvalve17 into pipe 18, which delivers to the condenser 19, and also topipe '20 through valve 2.1. In case the compressed air or any part ofsame is delivered to the bottom of the liquefying cone (13) throughvalve 15 and pipe 11, then valves 15 and 17' are closed, and valve 23 isopened, and the unliquefied air from the-liquefying cone (13) passes outthrough pipe 22 and valve 23 into pipe 18 and is delivered to thecondenser 19,

.same as before. This condenser (19) I make 5 (near the top) throughvalve 26, and up-` wardly bent discharge nozzles 25 so that theliquefied gas is discharged upward against the deflecting baffle member27.

The upper part of the rectifying column 5, at 5, and the middle part at5c are filled preferably with aluminum balls 5c1 and 5b about the sizeof peas. The pipe 20 is connected with the upper ring conduit 21 throughvalve 28.

At 29 I have a non-conducing fiber tube, which separates the condenser19 from the gases which pass up through the rectifying column. f

NAt y30 is shown the rectifying column low- 4pressure discharge conduitor the nitrogen vapor and re-cooled expanded nitrogen gas outlet pipe,which deliveisto the top of the counter-current interchanger drum 10.

Below'the liquefying cone coil (13) .I show a high-pressure liquefiedgas tank 31 or high-pressure receiver for the liquefied gas, whichliquefies in the liquefying cone and runs down by gravity throughconnecting pipe'32,and is collected in this receiver (3l). A siphonoutlet p'ipe 33, is fixed inside the receiver (31), its inlet being nearthe bottom, and which passes upward and discharges upwardly throughvalve 31 against the perforated plate 35, which separates the bottom oftheupper compartment 5a of the rectifying column from the top ofcompartment 5. This Siphon pipe (33) which cairies the liquefied gascollected inl receiver 31, up through successively the liquefying cone13, and the radially-grooved deflector 36 and compartment 5 of therectifying column, is preferably inclosed 'in and insulated by the fibertubes 37 and 37.

At 36 is shown iny improved radially corrugated or grooved liquefied gasrectifying deiiector or spreader, having radial grooves for de iveringthe liquefied gas (which comes down through the column 5) from theperipheral edge of said deflector (36) to the top of the helicalliquefying coils of the liquefying cone (13) inside the cone. Along theapexes of the raised portions or corrugations of the deflector 36between the radial grooves upon the top side thereof I have p providednumerous small holes which allow collected in the low-pressure reservoir3S,

surrounding the submerged high-pressure receiver 31, where it is stillfurther rectified by sub-cooling the liquefied gas in the receiver (31),absorbing therefrom its latent heat of vaporization; and such vapor asmay be thus produced in the reservoir 38 is also rectified and itsoxygen condensed as it passes up through the defiector 36 and rectifyingcolumn 5.

I supply the expansion engine 3 with compressed gas from pipe 10,through valve 11. This compressed gas is drawn from either ring conduit21 through pipe 18 and valve 21 or ring conduit 21 through pipe 20 audvalve 28 (preferably the latter), and being very cold it is passedthrough the coil 12 in the freezing dium 9, and is thereby re-lieated orraised in temperature by cooling the compressed air as it is deliveredfrom drum 7 into the freezing drum 9 through valve 12; the re-lieatedgas is then delivered to the cxpansion engine 3 through valve 11 andfeed pipe 10, and 'is expanded therein, the heat it has taken up fromthe compressed air in the drum 9 being transformed into external work onthe fly-wheel 1 of the airfcompressor (l). In this way the initialtemperature of the high tension gas as delivered to and immediatelybefore expansion in the engine 3 may be regulated as desired, so thatthe temperature of the expanded gas delivered through conduit 43, may bemaintained below the critical temperature of the compressed air in theliquefying cone 13. This cold expanded gas is given a helical coursedownward around the outside of the lique- .fying cone' (13) by thehelical -partition i plate 44.' During the operation-the coil 12 in thefreezing drum 9 will get covered with frost (being the last residueof-moisture in the compressed air treated), which may be melted anddrawn off through drip cock 45, by closing air cocks 42, 46 and 48, andcocks 21, 28 and 41, and opening air cock 47; in-

this way, by shutting off the water from the final cooler of thecompressor, hot air may be passed through the by-pass pipe 48 into thedrum 9. By this improved construction, this method of getting rid of theaccumulating frost, may be made use of any time without the disadvantageof stopping the opera- ,tion of the mechanism-the engine being ilbs-gage pressure. It is then finally watercooled, and is passed throughthe drums 6 and 7, and dust, moisture,y carbonic acid gas and otherforeign substances removed therefrom. From thence it is passed throughthe freezing drum 9, where it is cooled to from 40O to 100o F.. belowzero, by the cold gas passed through thel coils 12 in said drum. (Thegas passed through this coil 12 is the unliquefied gas from thehigh-pressure liquefiers.) All moisture remaining in thecompressed airis frozen out in passing through drum 9, and is deposited as frost onthe outside of the coil 12'. The pure, dry air is then conducted throughvalve 46 into theinterchanger coils 11 inthe interchanger drum 10 whereit is cooled to about 180o dry and pure compressed airis then deliveredthrough coil 11 and pipe 14 and the by-pass A51 tothe air-expansionengine 3,

` wherein itis' expandedagainst ,external resistance, doing work on thetfly-wheel (4) of the compressor, and itstemperature falls corlresponding to the amount of work done. This cold expanded air is thenconducted into the rectifying column 5, and is passed around theliquefyingcone coil 13, in the helical passage between the helicalplates 44,`and thenpassed between the lower coils (13) and under sameinto the insideof the cone around the fiber tube 37 and up through theperforations in the rectifying deflector 36 (being cooled thereby), andfinally up through the rectifying column and the discharge pipe 30 tothe lnterchanger 10, where it cools the engine supply of compressed airpassing through the coil 11. Very soon portions of the air in theliquefying coils 13 become liquefied and pass down through pipe 32 intothe high-pressure vreceiver 31. vWhen the receiver is full releasevalve34 is opened, and the liquid is forced upwardly through discharge pipe33 and after discharging upwardly against the perforated plate 35, itfalls down through or around the aluminum balls (5b) on totheradially-grooved rectifying deflector 36, and down over the insidesurfaces (cataractlike) of the liquefying cone 13, absorbing its latentheat of vaporization from the compressed air in the cone coil. By theemploylment of a liquefying cone coil all parts of the liquid air arebrought 'into indirect physica-l but indirect thermal contact with thecompressed air to be liquefied. This is due to the fact that the liquid(rich in oxygen) in the form of athin annular sheet drips over and in adirection at nearly right angles to the pipe ,for conduit carrying thecompressed air which is being liquefied; 'The said ,liquid falls down bygravity cataractlikev successively over the helical coils of the pipe orconduit containing the passing column of compressed air sought to beliquefied. This causes rapid fractional evaporation of the fallingliquid air, and the vapor passes upthroughm the fine perforations in theridges or along the apex of the radial and upwardly extendedcorrugations between the grooves in the deflect'or 36. As

Athis defiector is preferably made lof sheet copper (which has greatthermal conductivity) and as the grooves are filled with thelater-condensedvliquid air, the oxygen of the rising vapors becomescondensed and drips back; the rising gases becolne further recti-v fiedas they come in contact with the aluminum balls and descending liquid inthe fiber tube 29. Valve17 may now be opened (valve 23 remainingclosed), and the unliquefied gases in the liquefying cone 13 then passinto the upper or secondary liquefier 19,' through pipes 14C, 16 and 18.This secondary liquefier consists of the ring conduits 24 and 24 andnumerous connecting pipes 19 in the annular space between the walls ofthe non-conducting fiber tube 2,9 and the outer wall 5c of therectifying column. This annular space is open at the top and some of thecold liquid from the upwardly-delivering nozzle of valve 34, falls downaround the liquefyingtubes 19 and passes out under the lower end edgesof the fiber tube 29, on to the top of deflector 36, and thus liqueesmore or less of the unliquefied compressed gases ins'aid tubes, (19'),and such liquefied gas drips down into the ring conduit 21. lFrom thenceit is forced up through the siphon pipe 25 by opening valve 26, and isdelivered through the upwardly-delivering nozzle 25 against the bottoniof the protecting ballie 27, and then falls down through or around thealuminum balls 5 in the upper part (5a) of the rectifying column. Thisliquid being-considerably colder than liquid oxygen, still furtherrectilies the vapors and unliquefied 'gases passing up through therectifying column, by condensing toa liquidthe last portions of alloxygen in the rising gaseous vapors, and replacing same by vaporizednitrogen from the liquefied gas as it -falls down through or around thealuminum balls in both the upper and lower compartment of the rectifyingcolumn.V This'liquelied gas is practically Aall vaporized before itreaches the rectifying detlector 36. Valve 50 (which supplies theexpansion engine with compressed air from pipe 14) may now bepclosed,and valves 21 or 28 (preferably the latter) and l1, be opened. Then theengine will be supplied from pipe 40 with compressed gas from the top ofthe secondary liquefier, which will pass through pipe 20 into andthrough coil 12 (in the freezing drum 9),

where it is re-heated by cooling the compressed air in said drum, andfreezing out the moisture therefrom, which will be deposited asfrost onthe outside of coil 12. The initial temperature of the compressed gassupplied to the engine, immediately before expansion therein, .may beeasily regu- By the cup-like construction of the baille 27 at top of therectifying column, the inlet to pi e 30 is protected, so that only gases(pra tically pure cold nitrogen gas) is permitted to escape through pipe30; in the lower edges of this baille cup (27) there are small dripholes (27") to let out any liquid which 'gets into the cup. The oxygenwhich collects in the reservoir 38 may be drawn off in liquid formthrough cock 53.

One special feature of my invention is that in sub-cooling (or coolingafter lique faction) of the liquid under high .pressure in receiver 31,so that when it is released from pressure by valve 34 there is noVaporization, I utilize the latent heat of vaporization of thelow-pressure liquid in reservoir 38 (which is taken from the liquid inreceiver 31) when it is at the maximum (about 125 B. T. U.); and inpartially liquefying reciprocating engine, or a turbine, or any lated bythe degree of re-heating in drum` 9, by regulating the amount of gaspassed through the coil 12; any insulliciency of such supply,` may bemade up by opening. valve 50 and taking some air from pipe 1-1, or byopening valve v52 and taking some warmer air from the supply pipe beforeit enters the interchanger. By thus taking air or gas of differenttemperatures, and properly regulating the speed of the engine, anydesired initial temperature may be given the compressed gas supplied toand expanded in the engine: and in this Way any terminal temperaturedesired may be given to the expanded gas in conduit 43, as exhaustedfrom the expansion engine and delivered against the primary liquefier13--the desirable point being to maintain a temperature of such expandedgases below the critical temperature of liquefaction of -thehighpressure air in thc liquefying cone.

other mechanism that will` expand compressed gas or gaseous mixturesagainst external resistance, and thereby transform portions of theirheat into external work. I make no claim herein to the, novelconstruction of thisexpansion engine, nor to any other parts of theapparatus as herein shown, as the same will form the subject-matter ofanother application.

The coils 11 and 12, and the primary and secondary liquefiers 13 and 13and 19 and 19 with the ring conduits 24 and 24:', as well as receiver31, are all made preferably of copper, so as to insure the maximum ofthermal conductivity.

I claim asnew and original and desire to secure by Letters Patent, isi 1. The art or process of liquefying and separating a gaseousmixture,which cornprises compressing and cooling the mixed gas; delivering oneportion of said compressed mixed gas toa liquefier, and anotherportionto an expansion engine, and expanding the same therein againstexternal resistance; and then liquefying the gas lin--the liqueer whileunder compression by the combined refrigerative effect of the coldexpanded gas exhausted from the engine, andl liquefied gas previouslyliquefied in said liquefier but released from pressure--looth saidreleased liquefied gas and said cold expanded gas being conducted oversaid liqueier so as to absorb heat from but not in direct contact Withthe compressed gases being liquefied therein.

Q. The art or process of liquefying atmospheric air which comprisescompressing and cooling the air and partially 'liquefying the same,separating the liquefied from the unliqueed portion, and retaining thesaid unliquefied portion under lcompression and causing it to cool thecompressed air before partial liquefaction thereof.

3. The art or process of Iliquefying ai-r comprising the compressing andcooling of the air and causing partial liquefaction of the same undertension in a liqueier by the combined refrigerative effect of thereleased liquefied gas and expanded gaseous products of previousliquefaction iowing over said liquefier in contact With each other andin opposite directions.

4. The art or process of liquefying atmospheric air, which comprisescompressing the air; partially liquefying' a portion of such air Whileunder compression; separating thecold unliquefied gas from the liquidthusl obtained, and utilizing the l refrigerative effect of theunliquefied gas While under compression to cool the compressed air to betreated. p

5. The art or process of liquefying atmospheric air, comprising thecompressing and cooling of the air, and causing partial liquefaction ofthe same under tension in a liqueier by the combined refrigerat'e eiiectof the released liquid and expanded gaseous products of previousliquefaction flowingoVer said liquefier.

6. The art or process of liquefying atmospheric air and separating theconstituents thereof, oxygen and nitrogen, Which'comprises compressingand cooling the air, and

subjectingr the same to partial liquefaction in a plurality ofliqueflers, the resultant liquid collected from the first liqueier beingrich in oxygen and that'from a successive liqeier being rich innitrogen; separating the liquefied lfrom the unliquefied portions; andfinally'withdrawing the unliquefed gaseous residue under tension andexpanding the same, and utilizing the resultant refrigeration obtained,thereby in causing partial.-

liquefaction offurther, portions of compressed air as delivered to the'primary liquefier.

7. The art or process of liquefying'atmos-v pheric air and separatingtheconstituents thereof, oxygen and nitrogen, which comprises compressingand cooling the air, and subjecting the same to partial liquefactionunder pressure; separating the liquefied from the unliqueied portions,and releasing the liquid obtained from pressure, and evaporatingportions thereof, and expanding the unliquelied compressed gaseousresidue; and finally utilizing the combined refrigerative sioninpartially liquefying further portions of compressed air.

8. The art or process of liquefying atmospheric air and separating theconstituents thereof, oxygen and nitrogen, Which comprises compressingand coolin the air, and subjecting the same to parta liquefaction underlpressure in a plurality of liquefiers; separating the liquid obtainedin each liqueier from the unliquelied gases, and releasing from pressureseparately the liquids obtained in each liquefier, and evaporatingportions thereof at substantially atmos-J pheric pressure; withdrawingunder tension all of the unliquetied gaseous residue from the liqueiers,and expanding the same to the low pressure of the evaporating liquid;and inallyutilizing the combined refrigerative effect of suchevaporation and such expanof compressed air. s

9. rlhe art or process of liquefying atmospheric air and separating thesame into its lconstituents, oxygen and nitrogen, Which comprisescompressing and cooling the air, partially liquefying the same, andseparating under tension the liquid thus obtained from the unliquefiedportion; sub-cooling .95

said. liquid by the liquid products yof previous' similar liquefaction,and finally releasing said sub-cooled liquid products from pressure, andcausing separation of the constituents thereof by distillation.

\and expanding the gaseous residue; and .inally causing separation ofthe constltu-v ents of the. liquid obtained from said liqueier bydistillation thereof.

1l'. The art or process of liquefying at- `rnospheric air and separatingthe same into its constituents, oxygen and nitrogen, Which ,comprisescompressing and cooling the air;

partially liquefying the same in a plurality of liqueiers under tension,and sub-cooling of the liquid products thus obtained While underpressure*l by the liquefied portions previously produced in asimilarmanner and released from pressure; releasing from pressure the saidcooled liquid products of liquefaction and expanding the unliqueedgaseous residue; and iinally Causing separation sion in partiallyliquefying further portions of the. constituents of the liquid collectedfrom the respective liquefiers byV distillation of said released liquidproducts. "f

` 12 The art or process of liquefying at-A mospheric air and separatingit into its component parts, oxygenand nitrogen, which comprises thecausing of a partial liquefaction thereof` in a plurality of liquefiers,separating the'lquid obtained in each liquefier from the unliquefiedportion, releasing from pressure the liquids obtained in each liqueficrand introducing the same into a rectifying column, and withdrawing theunliquefied portions from said-liquefiers.

13. Tlieyart or process of liquefying atlniosplieric air and separatingit into its component parts, oxygen and nitrogen, which comprisesthecausing of a partial liquefaction of the air in a primary liquefiei,separating the liquid obtained in such liquelier from the unliquefiedportion of gas, introducing the said unliquefied portion of gas into asecondary liquefier and causing partial liquefaction thereof therein,separating the liquid obtained in such secondary'liquefier from theunliquefied portion of gas, and releasing from pressure separately theliquids obtained in said liquefiers, introducing the saine into arectifying column and evaporating portions thereof at substantiallyatmospheric pressure in thermal contact with the gases within the saidvliquefiers.

14. The art or process of liquefying atmospheric air and separating itinto its component parts, oxygen and nitrogen, which comprises thecausing of a partial liquefaction of the aii in a primary liqucfier,

' separating the liquid obtained in such liquefier from thei'inliquefied portion of gas, in-

troducing the said unliquefied portion of gas into a secondary liquefierand causing partial liquefaction thereof therein, separating the liquidobtained in such secondary liquefierfrom the unliquefied portion of gas,and releasing fromv pressure separately the liquids obtained in saidliquefiers, introducing the same into a rectifying column andevaporating portions thereof at substantially atmospheric pressure inthermal contact with the gases within the said liquefiers, andwithdrawing uiider tension all the unliquefied y gaseous residue fromthe secondary liquefier yand expanding the same to the low pressure ofthe evaporating liquid.

' 15. The process of separating atmospheric air into oxygen and nitrogenwhich comprises compressing and cooling the airand liquefying a portionthereof in contact with a portion which is not liquefied and thensubjecting both portions while under presduced under pressure during the*.piocess, then separating the liquefied gases from the.

unliquefied and finally releasing thev liquefiedgases from pressure andexpanding the unliquefied gaseous residue with production of recoverableexternal work. A

1 6. The process of liquefying air and separating the oxygen from thenitrogen thereof which comprises compressing and cooling the air andthen liquefying it while under pressure by bringing it in thermal butnot physical contact with a descending or dripping liquefied gasreleased from pressure and being fractionally distilled or evapo ated byheat drawn from the compressed air being liquefied.

17. The process of liquefying air and separating the oxygen from thenitrogen thereof which consists in compressing and cooling gaseous air,passing previously liquefied portions of air over said cooled compressedair iii thermal but not in direct contact therewith, liquefying a.portion of the compressed and cooled air in contact with a portionthereof which is not liquefied and separating the liquid tlius-obtainedfrom the gaseous residue, and finally vliquefying portions of y saidgaseous residue, separating the liquefied from thel unliquefied 'portionand releasing this final liquid from pressure and expanding the finalgaseous residue.

18. The process of liquefying and separating a gaseous mixture into itsconstituents which consists in compressing and cooling the same,partially liquefying the same while under compression, separating theliquefied from the unliquefied portions, partially liquefying theunliquefied residue,4 then employing the remaining portion of suchunliquefied residue to cool other portions of air, thereafter expandingsuch remaining portion and using said expanded portion to assist incausing the partial liquefaction first referred to above.

Signed at New York city in the county of New York and State of.New Yorkthis 3d day of February, A. D. 1911.

' JAMES F. PLACE.

Witnesses:

LAURA E. Siui'rii, M. GoLnsrniN.

